PSP POPSloader 6.60 PRO (PS1 on PSP) 2018-01-31

For whatever reason, certain games work best on certain firmwares.
What popsloader does is enables you to change the PSP into thinking it’s on a certain firmware for said game.

People who have been on the scene for a while know about popsloader, a heavy modification of Sony’s PS1 emulator that allows us to run PS1 backups on our PSPs (yes, once again, you can run more legal content on a hacked psp than on an official one, since Sony doesn’t provide a way for PS1 game owners to play their own games on the psp without buying them a second time… and even if you’re willing to do that, the PSN Store doesn’t have all the ps1 games).

To use- simply hold the right trigger when booting a PS1 eboot, and select which version of pops you'd like to use.